The invention relates more particularly to apparatus for supporting a preform manufactured or built up in an installation for manufacturing or building up preforms having central cores. This type of installation conventionally includes at least translation means and rotation means having a horizontal axis of rotation and on which the supporting core of the preform to be manufactured or built up is mounted, and plasma-torch and material-supply means disposed radially relative to said supporting core so as to make or build up said preform by coating.
The rotation means rotate the supporting core, and the plasma-torch and material-supply means are moved in axial translation parallel to the supporting core so as to deposit the layers making up the preform being manufactured on the supporting core using known principles and/or methods. In a variant, the preform is moved in translation while the torch remains stationary.
Such means are also implemented for "building up" an existing preform so as to thicken it.
After manufacturing or building up the preform, a cooling stage is currently necessary prior to the preform cutting stage during which the preform is cut manually. During the cutting stage, an operator inserts a support under the preform and cuts the preform by means of a blow-torch or the like. The cooling stage is a safety requirement made necessary by the presence of the operator.
Such a method gives rise to a significant loss of time due to preform cooling. Any shortening of the cooling stage considerably increases operator accident risks. However, locally re-heating a cooled preform, during the cutting stage, can have considerable adverse effects on the uniformity and the optical qualities of the preform in the re-heated zone. In particular, cracks may occur. It is therefore necessary to strike a compromise between quality and safety as a result of the human presence during the cutting stage.
Furthermore, the size of a preform is currently limited in particular by its weight. The preform sags under its own weight. Such sagging runs the risk of breaking an end-piece. Moreover, such sagging can have adverse effects on the uniformity of the preform.